Firearm



uly 21, 19 N. 1.. BREWER 2,290,156

FIREARM Filed Feb. 19, 1940 2 Sheets-Sheet 1 INVENTOR NICHOLAS L. BREWER M&W

ATTORNEYS July 21, 1942. N. BREWER FIREARM 2 Sheets-Sheet 2 Filed Feb. 19, 1940 INVENTOR NICHOLAS BREWER & W

ATTORNEY,

Patented July 21, 1942 i FIREARM Nicholas L. Brewer, East Longmeadow, Mass, as-

signor to Savage Arms Corporation, New York, N. Y., a corporation of Delaware Application February 19, 1940, Serial No. 319,648

Claims.

This invention relates to semi-automatic or automatic guns of the blow-back type. The general purpose of this invention is to provide a new and improved form of blow-back or automatic gun and particularly to provide new and improved ways for venting the gun so that the venting allows for the dispersal or scattering of the blast of gas and materials carried thereby in a safe and eifective way and also in such a manner that the force of the blast is effective to prevent the deposit of these waste materials on the parts of the action of the gun and particularly to prevent such waste materials from being deposited at or near the joint between the forward end of the breech bolt and the rear end of the barrel.

When the action opens in a blow-back or automatic gun, a blast of gas emerges from the barrel directed rearwardly, but at the same time, expanding in all directions laterally. This blast of gas carries with it powder residue and bullet lubricant in a more or less melted form. The powder residue consists of grains of burnt powder, a somewhat soot-like deposit, and generally some grains of unburned powder.

When no specific means are provided for the escape of this blast of gas, the fouling, that is to say, the mixture of bullet grease and powder residue is forcibly blown back into the various parts of the action adjoining, and to the rear. The accumulation of this fouling in the parts of'the action will, in a relatively short time, cause the various parts to stick and fail to function properly,

In a gun of this type, that is to.say, a semiautomatic or automatic blow-back gun, this condition renders the gun inoperative, or at least unreliable. It is, therefore, advisable to provide as generous a means of escape for the gas and the fouling carried thereby as possible.

Since there is generally an opening located on the right-hand side for the ejection of the empty shell or the loading of a live cartridge by hand when the gun is used as a single shot, the gas and fouling have some means of escape to the right. This, however, is not sufi'icient.

I have, therefore, provided in this improved blow-back, or automatic gun an Opening on the left-hand side. If this opening were simply one large hole, approximately like the port on the right-hand side, the gas could come out in such a direction as to be directed back into the face of the shooter. While providing a sufficient exit, as far as fouling is concerned, this kind of an opening would be obviously unsuitable. It is necessary to allow the escape of the fouling and the gas which carries it in such a way that none of it .can be directed back towards the shooters face.

I have accomplished this by making the opening on the left-hand side consist of a series of substantially vertical slots, having such a width in relation to the thickness of the wall of the receiver that no gas or particles of fouling can be directed to the rear at an angle of less than about 45 degrees with the axis of the gun, which gun axis is the basis of all the angles herein mentioned. This permits the necessary escape of the fouling without the possibility of any of it .being directed back into the shooters face.

The important feature is the relation of the width of each individual slot to the thickness of the wall of the receiver. It can readily be seen that the narrower the slot relative to the receiver wall thickness, the less the gas can be directed rearwardly, while on the other hand the greater the width of the slot, the more the gas can be directed rearwardly.

While for convenience and cheapness of manufacture I have out these slots at right angles to the axis of the receiver, they could be cut slanting forwardly as they extend outwardly, so that the gases, upon passing through them would be deflected either straight out to the side or even slightly ahead. This should be considered as an alternate construction and as a modified form of the invention.

In addition to allowing the fouling to get out of the gun, it should be noted that the front slot is located so that it occurs at the junction of the back end of the barrel and the front end of the breech bolt. The loading and ejection port on the right-hand side is either carried ahead, or another slot is provided so that this junction is also open to the outside on the righthand side.

The purpose of this is to allow the blast of gas upon the opening of the action when the gun is fired to sweep these joining surfaces clear of any accumulation of bullet grease, powder residue or foreign material or dirt of any sort.

If an accumulation of any sort, whatsoever, is allowed to build up on either of these joining surfaces, the breech bolt cannot be fully closed, and the space remaining thereby for the rim of the cartridge is too great. This excess head space, as it is known, can and frequently does result in the rim of the cartridge bursting violently when the gun is fired. This is a very serious and undesirable thing to happen. I, therefore, believe that this clearing by the blast of gas of these joining surfaces is a very impor tant part of the invention.

Fig. 1 is a side elevation of the relevant portion of a gun embodying the preferred form of my invention, with the gun stock cut away on a central vertical longitudinal line.

Fig. 2 is a top plan view of the portion of the gun shown in Fig. 1 but entirely omitting the stock.

breech bolt has begun its rearward movement,-

but with the empty shell of the fired cartridge still having its forward portion within the chamber of the barrel.

Fig. is a view similar to Fig. 4 but after the breech bolt has continued its rearward motion" far enough to slightly withdraw even the forward end of the shell of the cartridge from the barrel.

Fig. 6 is a view similar to Figs. 3, 4 and 5 but with the breech bolt still further to the rear than shown in Fig; 6 and with the shell of the cartridge shown as being ejected from the receiver of the gun.

Fig. '7 is a transverse section through the receiver of the gun as on line 1-1 of Fig. 3, but of a complete gun. V

Fig. 8 is a top or plan view similar to Fig. 2 butshowing a modified form of the invention.

Referring to the drawings in a more particular description it will be seen that there is illustrated the pertinent parts of the action of a semiautomatic gun of the blow-back type wherein the conventional barrel It has secured towards its rear end a conventional form of receiver II in which is reciprocatingly mounted the breech bolt l2. Said breech bolt is adapted on its rearward movement to extract the empty shell I3 of the fired cartridge from the-chamber Id' of the barrel and eject said shell to the right through the port i5 in the right-hand wall of the receiver H, which port functions as the normal ejection port both when the gun is used as strictly a semi-automatic gun and also when the gun is used as a single shot or hand-operated gun. Said port [5 also functions'as a port for the loading therethrough of the new cartridges when the gun is being used as a single shot or hand operated gun. Conventional mechanism is also present but not necessary to be described here in detail, for receiving a new cartridge from the tubular magazine 16 and moving it up through the center of the receiver tothe rear end of the barrel and to a point more or less in front of the breech bolt f2, which on its forward motion pushes such cartridge forwardly into the chamber of the barrel. The details of such feeding mechanism, and for moving the breech block forward and closing the same form no part of this invention and therefore it is deemed that a description thereof is unnecessary. Furthermore it will be noted particularly that my invention is not limited in its application toany particular form of feeding mechanism or action mechanism in a blow-back semi-automatic gun, but is applicable and is intended herein to be widely applicable and is claimed widely as an invention without reference to the feed or action mechanism or the magazine mechanism or a combination of any of these parts.

The essential part of my invention is to provide a series of venting openings I! on the left hand side of the receiver H. In the preferred form of the invention as shown in Figs. 1 to 7 inclusive these openings ll are arranged at a right angle to the longitudinal axis of the receiver H and are in the main opposite to the ejection and loading port I5.

In practice these slots l1 will be formed by cutting away the material from the wall of the cylindrical receiver as by a suitable milling machine or other equivalent mechanical means, until the slots ll are formed in proper spaced relation and extending through the proper portion of the total circumference of the receiver, leaving webs or partitions l3 between adjacent slots. Preferably, as plainly shown in Fig. '7, the slots IT or venting openings will be symmetrical in arrangement, with theejection opening or port IS on the right hand side of the receiver. In other Words the slots ll will come about as near to the central line of the top wall of the receiver as does the upper portion of the ejection port l5, and likewise the lower end of the venting slotsl1 will extend downwardly towards the bottom center line of the receiver about as far as does the bottom end ofthe forward ejection port I5. In the preferredform of my invention as shown in Figs. 1 to '7 inclusive the slots I! are located at right angles to the longitudinal axis of the receiver but as shown in Fig. 8 of the drawings my invention also includes as an alternative form the modification wherein the venting slots l9 slant forwardly as-they go out'from the receiver and the intervening webs or partitions 20 similarly slant forwardly.

As will be seen from observing. Figs. 1 to 6 of the drawings the venting slots ll which extend outwardly at right angles to the longitudinal axis of the receiver are of a width preferably substantially equal to the thickness of the wall of the receiver at this point. By width of the slots I1 is meant their extent from frontto rear along the wall of the receiver. I have found that this approximate proportion is a very workable,.con

venient, eliable, and efficient proportion of the slots ll so as to get a sufficiently free exit for the waste gases and materials carried thereby and yet prevent a possible deflection of the blast of these gases from going so far to the rear as to be thrown into the face of the shooter.

At the instant the forward end of the empty case 13 of the cartridge clears the rear end of the barrel chamber [4, the gas begins to escape at first radially from the infinitely small space between the front edge of the shell and the rear edge of the barrel, but this blast of gas soon begins to spread forwardly and rearwardly and as the shell-moves still further rearwardly the dispersal of the blast of gas becomes more general and fills the space between the shell of the cartridge and the inner wall of the receiver. A lot of the gas findsits exit through the large ejection port IE but fully an equal amount tends to pass to the left and seeks an outlet through the several venting slots I'l. As the cartridge shell l3 arrives at the position shown in Fig. 5 the escape from the rear end of the barrel becomes more general and as the shell passes still further to the rear following the rapid rearward movement of the breech bolt in a semi-automatic blow-back gun the gases gradually extend their path of escape through even the more rearward venting slots.

Referring to Fig. 5 it may be stated that the slanting line designated by the letter A indicates the most rearwardly slanting line which the gas may take through any of the venting slots [1. It will be seen that the path of this blast of gas is limited by the inner edge of the front web or partition of any particular venting slot and is also limited by the outer edge of the web to the rear of such venting slot, and that accordingly gas passing in this angular direction but in a straight line as indicated by the line A will pass outwardly and rearwardly at an angle not less than 45 degrees with the axis of the gun. It is obvious from this illustration and from an inspection of the drawings that any gas making its exit from any of the slots at any position of the breech bolt cannot pass rearwardly at an angle less than 45 degrees relative to the axis of the gun.

Obviously by decreasing the width of the venting slots IT to less than the thickness of the receiver wall, the possible rearward inclination of the gases Will be proportionately reduced, viz: Will be at a greater angle relative to the axis of the gun, but I have found that the arrangement of these venting slots as shown in Figs. 1 to 6, and with the width of the slot approximating that of the thickness of the wall of the receiver, combine to make a sufficiently easy and direct exit for the escape of gas from the blow-back of the gun with a limiting of the rearward direction of the blast of gas to a direction not less than 45 degrees with the axis of the gun and that this rearward inclination of some of the gases is not excessive but is practically safe for the shooter and does get such an abundant exit for the gases that the force of the blast tends to blow out of the receiver and away from the action any residue of the gas or any foreign material carried thereby.

Experience has demonstrated that the powder residue and bullet lubricant carried by the gas tend to stick or adhere to the rear end of the barrel and particularly to the forward end of the breech bolt and especially at the junction faces of these two parts. It is well knownthat these two parts should come very intimately together when the action of the gun is closed and that even a slight displacement of the breech bolt from this desired perfect forward position, producing what is known in the art as excess head space, may be disastrous in its results, causing explosions of cartridges through the rims thereof. It is therefore highly desirable that the joint portions of the barrel and of the breech bolt should be kept as clear as possible of powder residue and bullet lubricant. In the ordinary conventional form of blow-back semi-automatic gun the ejection port l5 does not extend forwardly to a line opposite the rear of the barrel and the front of the breech bolt and therefore if no supplemental venting slot were provided on the right hand side of the receiver forward of the ejection port I5, and if the venting ports I! already mentioned did not extend far enough forward to be in line with these junction faces or approaching faces of the breech bolt and barrel there would be no blast or current of gas past these two parts until the breech bolt had moved far enough to the rear to begin to sharply reduce the current or force of the blast of the gas. Accordingly I have provided in the right hand wall of the receiver a supplemental venting slot 2| cut into that wall of the receiver, and leaving to the rear of that slot a web 22 of the original material of the receiver, which web conveniently provides a guide for the proper alignment of the breech bolt relative to the bore of the barrel. Similarly in the modified form of Fig. 8 using slanting slots J9 and slanting webs on the left-hand side, I

provide directly at the rear line of the barrel and on the right hand side of the receiver slightly forward of the ejection port a slanting venting slot 23. This is made exactly as already described for the general slots 19 at the left hand side but this slot is especially important in that as soon as any gas is free to escape from the rear end of the barrel it can pass directly outwardly radially of the receiver and closely along the adjacent rear face of the barrel and the forward face of the breech bolt and so will directly tend to keep the said faces clear of powder residue or bullet lubricant or any foreign material. The material of the receiver left back of this forward- 7 1y located, slot 23 forms a web 24 which like web 22 back of the foremost slot 2| on the right hand side of the receiver of Figs. 2, 5 and 7 serves as a guide for the breech bolt.

What I claim as new and desire to patent is:

1. For an automatically-loaded shoulder-held gun, a receiver slotted with a series of closely spaced slots on its left-hand side beginning at the rear end of the barrel said slots extending normal to the axis of the receiver and severally having a width substantially equal to the thickness of the receiver, and extending for a least one-fifth the circumference of the receiver, for the rapid and harmless vent of gases and the expulsion of fouling material carried thereby.

2. For a semi-automatic gun having a barrel and a breech member adapted to closely fit the rear end thereof, a receiver extending rearwardly from the barrel and reciprocatingly mounting said breech member andhaving in its left-hand side a series of spaced gas-venting slots beginning at the rear end of the barrel, all said gasventing slots extending approximately one-quarter of the circumference of the receiver.

3. For a semi-automatic gun having a barrel and a breech member adapted to closely fit the rear end thereof, a receiver extending rearwardly from the barrel and reciprocatingly mounting said breech member and having a cartridge case ejection opening at its right-hand side to the rear of the barrel and a gas-venting slot in its right-hand side closely forward of said ejection opening and having in its left-hand side a series of spaced gas-venting slots beginning at the rear end of the barrel, all said gas-venting slots extending approximately one-quarter of the circumference of the receiver.

4. For an automatically-loaded shoulder-held gun having a barrel and a breech member adapted to closely fit the rear end thereof, a receiver extending rearwardly from the barrel and slidingly housing said breech member and provided on its left-hand side beginning at the rear end of the barrel with a plurality of closely spaced gas-venting slots extending approximately onequarter of the circumference of the receiver.

5. For an automatically-loaded shoulder-held gun having a barrel and a breech member adapted to closely fit the rear end thereof, a receiver extending rearwardly from the barrel and slidingly housing said breech member and provided on its left-hand side beginning at the rear end of the barrel with a plurality of closely spaced gasventing slots extending at least one-sixth of the circumference of the receiver.

NICHOLAS L. IBRIELWER. 

